<p>Ambiguous or uncertain sensory information is often resolved by incorporating prior assumptions about the most likely interpretation. Similar neural structures and a common visual environment typically lead to homogeneous priors in the population. Ambiguous motion displays are a rare exception as sustained idiosyncratic directional preferences have been observed. Patients with schizophrenia spectrum disorder (SSD) have been shown to rely less on perceptual priors in some contexts, yet their idiosyncratic directional preferences in ambiguous motion perception remain unexplored. Directional preferences were measured in two ambiguous displays: apparent motion and transparency-from-motion. To assess the strength and temporal stability of these preferences, we conducted measurements at two time points: first, during the acute phase of SSD in 32 hospitalized patients, and second, after symptom remission. A matched group of 18 healthy controls was also tested at comparable intervals. We found that patients exhibit idiosyncratic directional preferences that are similar in strength and stability as in healthy observers. Across patients and controls, the preference strength was positively correlated with performance in the d2-test, which measures selective and sustained attention. Apart from that, there was no evidence that the severity of positive or negative symptoms across time or the performance in a visuo-spatial working memory task would be related to the directional preferences. These findings suggest that certain perceptual priors can be preserved in SSD, regardless of symptom status, with attentional resources playing a crucial role in determining the strength and stability of directional preferences.</p>